UIDynamicBehavior 驱动自定义转换
https://i.stack.imgur.com/VAeNo.gif
此示例显示如何创建由复合 UIDynamicBehavior 驱动的自定义演示文稿转换。我们可以从创建呈现视图控制器开始，该控制器将呈现模态。
迅速
class PresentingViewController: UIViewController
{
lazy var button: UIButton =
{
let button = UIButton()
button.translatesAutoresizingMaskIntoConstraints = false
self.view.addSubview(button)
button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive
= true
button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
button.setTitle("Present", for: .normal)
button.setTextColor(UIColor.blue, for: .normal)
return button
}()
override func viewDidLoad()
{
super.viewDidLoad()
button.addTarget(self, action: #selector(self.didPressPresent), for: .touchUpInside)
}
func didPressPresent()
{
let modal = ModalViewController()
modal.view.frame = CGRect(x: 0.0, y: 0.0, width: 200.0, height: 200.0)
modal.modalPresentationStyle = .custom
modal.transitioningDelegate = modal
self.present(modal, animated: true)
}
}
Objective-C
@interface PresentingViewController ()
@property (nonatomic, strong) UIButton *button;
@end
@implementation PresentingViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[self.button addTarget:self action:@selector(didPressPresent) forControlEvents:UIControlEventTouchUpInside];
}
- (void)didPressPresent
{
ModalViewController *modal = [[ModalViewController alloc] init];
modal.view.frame = CGRectMake(0.0, 0.0, 200.0, 200.0);
modal.modalPresentationStyle = UIModalPresentationCustom;
modal.transitioningDelegate = modal;
[self presentViewController:modal animated:YES completion:nil];
}
- (UIButton *)button
{
if (!_button)
{
_button = [[UIButton alloc] init];
_button.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:_button];
[_button.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = YES;
[_button.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = YES;
[_button setTitle:@"Present" forState:UIControlStateNormal];
[_button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
}
return _button;
}
@end
当点击当前按钮时，我们创建一个 ModalViewController 并将其演示样式设置为 .custom 并将其 transitionDelegate 设置为自身。这将允许我们出售将驱动其模态转换的动画师。我们还设置了 modal 的视图框架，因此它将比全屏小。
我们现在来看看 ModalViewController：
迅速
class ModalViewController: UIViewController
{
lazy var button: UIButton =
{
let button = UIButton()
button.translatesAutoresizingMaskIntoConstraints = false
self.view.addSubview(button)
button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive
= true
button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
button.setTitle("Dismiss", for: .normal)
button.setTitleColor(.white, for: .normal)
return button
}()
override func viewDidLoad()
{
super.viewDidLoad()
button.addTarget(self, action: #selector(self.didPressDismiss), for: .touchUpInside)
view.backgroundColor = .red
view.layer.cornerRadius = 15.0
}
func didPressDismiss()
{
dismiss(animated: true)
}
}
extension ModalViewController: UIViewControllerTransitioningDelegate
{
func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning?
{
return DropOutAnimator(duration: 1.5, isAppearing: true)
}
func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning?
{
return DropOutAnimator(duration: 4.0, isAppearing: false)
}
}
Objective-C
@interface ModalViewController () <UIViewControllerTransitioningDelegate>
@property (nonatomic, strong) UIButton *button;
@end
@implementation ModalViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[self.button addTarget:self action:@selector(didPressPresent) forControlEvents:UIControlEventTouchUpInside];
self.view.backgroundColor = [UIColor redColor];
self.view.layer.cornerRadius = 15.0f;
}
- (void)didPressPresent
{
[self dismissViewControllerAnimated:YES completion:nil];
}
- (UIButton *)button
{
if (!_button)
{
_button = [[UIButton alloc] init];
_button.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:_button];
[_button.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = YES;
[_button.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = YES;
[_button setTitle:@"Dismiss" forState:UIControlStateNormal];
[_button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
}
return _button;
}
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
return [[DropOutAnimator alloc]initWithDuration: 1.5 appearing:YES];
}
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
return [[DropOutAnimator alloc] initWithDuration:4.0 appearing:NO];
}
@end
在这里，我们创建了呈现的视图控制器。另外因为 ModalViewController 是它自己的 transitioningDelegate，它还负责出售一个将管理其过渡动画的对象。对我们来说，这意味着传递我们的复合 UIDynamicBehavior 子类的实例。
我们的动画师将有两个不同的过渡：一个用于呈现，一个用于解雇。为了呈现，呈现视图控制器的视图将从上方落入。而对于解雇，视图似乎从一根绳子摆动然后辍学。因为 DropOutAnimator 符合 UIViewControllerAnimatedTransitioning 这项工作的大部分将在 func animateTransition(using transitionContext: UIViewControllerContextTransitioning) 的实施中完成。
迅速
class DropOutAnimator: UIDynamicBehavior
{
let duration: TimeInterval
let isAppearing: Bool
var transitionContext: UIViewControllerContextTransitioning?
var hasElapsedTimeExceededDuration = false
var finishTime: TimeInterval = 0.0
var collisionBehavior: UICollisionBehavior?
var attachmentBehavior: UIAttachmentBehavior?
var animator: UIDynamicAnimator?
init(duration: TimeInterval = 1.0, isAppearing: Bool)
{
self.duration = duration
self.isAppearing = isAppearing
super.init()
}
}
extension DropOutAnimator: UIViewControllerAnimatedTransitioning
{
func animateTransition(using transitionContext: UIViewControllerContextTransitioning)
{
// Get relevant views and view controllers from transitionContext
guard let fromVC = transitionContext.viewController(forKey: .from),
let toVC = transitionContext.viewController(forKey: .to),
let fromView = fromVC.view,
let toView = toVC.view else { return }
let containerView = transitionContext.containerView
let duration = self.transitionDuration(using: transitionContext)
// Hold refrence to transitionContext to notify it of completion
self.transitionContext = transitionContext
// Create dynamic animator
let animator = UIDynamicAnimator(referenceView: containerView)
animator.delegate = self
self.animator = animator
// Presenting Animation
if self.isAppearing
{
fromView.isUserInteractionEnabled = false
// Position toView just off-screen
let fromViewInitialFrame = transitionContext.initialFrame(for: fromVC)
var toViewInitialFrame = toView.frame
toViewInitialFrame.origin.y -= toViewInitialFrame.height
toViewInitialFrame.origin.x = fromViewInitialFrame.width * 0.5 - toViewInitialFrame.width * 0.5
toView.frame = toViewInitialFrame
containerView.addSubview(toView)
// Prevent rotation and adjust bounce
let bodyBehavior = UIDynamicItemBehavior(items: [toView])
bodyBehavior.elasticity = 0.7
bodyBehavior.allowsRotation = false
// Add gravity at exaggerated magnitude so animation doesn't seem slow
let gravityBehavior = UIGravityBehavior(items: [toView])
gravityBehavior.magnitude = 10.0
// Set collision bounds to include off-screen view and have collision in center
// where our final view should come to rest
let collisionBehavior = UICollisionBehavior(items: [toView])
let insets = UIEdgeInsets(top: toViewInitialFrame.minY, left: 0.0, bottom: fromViewInitialFrame.height * 0.5 - toViewInitialFrame.height * 0.5, right: 0.0)
collisionBehavior.setTranslatesReferenceBoundsIntoBoundary(with: insets)
self.collisionBehavior = collisionBehavior
// Keep track of finish time in case we need to end the animator befor the animator pauses
self.finishTime = duration + (self.animator?.elapsedTime ?? 0.0)
// Closure that is called after every "tick" of the animator
// Check if we exceed duration
self.action =
{ [weak self] in
guard let strongSelf = self,
(strongSelf.animator?.elapsedTime ?? 0.0) >= strongSelf.finishTime else { return }
strongSelf.hasElapsedTimeExceededDuration = true
strongSelf.animator?.removeBehavior(strongSelf)
}
// `DropOutAnimator` is a composit behavior, so add child behaviors to self
self.addChildBehavior(collisionBehavior)
self.addChildBehavior(bodyBehavior)
self.addChildBehavior(gravityBehavior)
// Add self to dynamic animator
self.animator?.addBehavior(self)
}
// Dismissing Animation
else
{
// Create allow rotation and have a elastic item
let bodyBehavior = UIDynamicItemBehavior(items: [fromView])
bodyBehavior.elasticity = 0.8
bodyBehavior.angularResistance = 5.0
bodyBehavior.allowsRotation = true
// Create gravity with exaggerated magnitude
let gravityBehavior = UIGravityBehavior(items: [fromView])
gravityBehavior.magnitude = 10.0
// Collision boundary is set to have a floor just below the bottom of the screen
let collisionBehavior = UICollisionBehavior(items: [fromView])
let insets = UIEdgeInsets(top: 0.0, left: -1000, bottom: -225, right: -1000)
collisionBehavior.setTranslatesReferenceBoundsIntoBoundary(with: insets)
self.collisionBehavior = collisionBehavior
// Attachment behavior so view will have effect of hanging from a rope
let offset = UIOffset(horizontal: 70.0, vertical: fromView.bounds.height * 0.5)
var anchorPoint = CGPoint(x: fromView.bounds.maxX - 40.0, y: fromView.bounds.minY)
anchorPoint = containerView.convert(anchorPoint, from: fromView)
let attachmentBehavior = UIAttachmentBehavior(item: fromView, offsetFromCenter: offset, attachedToAnchor: anchorPoint)
attachmentBehavior.frequency = 3.0
attachmentBehavior.damping = 3.0
self.attachmentBehavior = attachmentBehavior
// `DropOutAnimator` is a composit behavior, so add child behaviors to self
self.addChildBehavior(collisionBehavior)
self.addChildBehavior(bodyBehavior)
self.addChildBehavior(gravityBehavior)
self.addChildBehavior(attachmentBehavior)
// Add self to dynamic animator
self.animator?.addBehavior(self)
// Animation has two parts part one is hanging from rope.
// Part two is bouncying off-screen
// Divide duration in two
self.finishTime = (2.0 / 3.0) * duration + (self.animator?.elapsedTime ?? 0.0)
// After every "tick" of animator check if past time limit
self.action =
{ [weak self] in
guard let strongSelf = self,
(strongSelf.animator?.elapsedTime ?? 0.0) >= strongSelf.finishTime else { return }
strongSelf.hasElapsedTimeExceededDuration = true
strongSelf.animator?.removeBehavior(strongSelf)
}
}
}
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval
{
// Return the duration of the animation
return self.duration
}
}
extension DropOutAnimator: UIDynamicAnimatorDelegate
{
func dynamicAnimatorDidPause(_ animator: UIDynamicAnimator)
{
// Animator has reached stasis
if self.isAppearing
{
// Check if we are out of time
if self.hasElapsedTimeExceededDuration
{
// Move to final positions
let toView = self.transitionContext?.viewController(forKey: .to)?.view
let containerView = self.transitionContext?.containerView
toView?.center = containerView?.center ?? .zero
self.hasElapsedTimeExceededDuration = false
}
// Clean up and call completion
self.transitionContext?.completeTransition(!(self.transitionContext?.transitionWasCancelled ?? false))
self.childBehaviors.forEach { self.removeChildBehavior($0) }
animator.removeAllBehaviors()
self.transitionContext = nil
}
else
{
if let attachmentBehavior = self.attachmentBehavior
{
// If we have an attachment, we are at the end of part one and start part two.
self.removeChildBehavior(attachmentBehavior)
self.attachmentBehavior = nil
animator.addBehavior(self)
let duration = self.transitionDuration(using: self.transitionContext)
self.finishTime = 1.0 / 3.0 * duration + animator.elapsedTime
}
else
{
// Clean up and call completion
let fromView = self.transitionContext?.viewController(forKey: .from)?.view
let toView = self.transitionContext?.viewController(forKey: .to)?.view
fromView?.removeFromSuperview()
toView?.isUserInteractionEnabled = true
self.transitionContext?.completeTransition(!(self.transitionContext?.transitionWasCancelled ?? false))
self.childBehaviors.forEach { self.removeChildBehavior($0) }
animator.removeAllBehaviors()
self.transitionContext = nil
}
}
}
}
Objective-C
@interface ObjcDropOutAnimator() <UIDynamicAnimatorDelegate, UIViewControllerAnimatedTransitioning>
@property (nonatomic, strong) id<UIViewControllerContextTransitioning> transitionContext;
@property (nonatomic, strong) UIDynamicAnimator *animator;
@property (nonatomic, assign) NSTimeInterval finishTime;
@property (nonatomic, assign) BOOL elapsedTimeExceededDuration;
@property (nonatomic, assign, getter=isAppearing) BOOL appearing;
@property (nonatomic, assign) NSTimeInterval duration;
@property (nonatomic, strong) UIAttachmentBehavior *attachBehavior;
@property (nonatomic, strong) UICollisionBehavior * collisionBehavior;
@end
@implementation ObjcDropOutAnimator
- (instancetype)initWithDuration:(NSTimeInterval)duration appearing:(BOOL)appearing
{
self = [super init];
if (self)
{
_duration = duration;
_appearing = appearing;
}
return self;
}
- (void) animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
// Get relevant views and view controllers from transitionContext
UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *fromView = fromVC.view;
UIView *toView = toVC.view;
UIView *containerView = transitionContext.containerView;
NSTimeInterval duration = [self transitionDuration:transitionContext];
// Hold refrence to transitionContext to notify it of completion
self.transitionContext = transitionContext;
// Create dynamic animator
UIDynamicAnimator *animator = [[UIDynamicAnimator alloc]initWithReferenceView:containerView];
animator.delegate = self;
self.animator = animator;
// Presenting Animation
if (self.isAppearing)
{
fromView.userInteractionEnabled = NO;
// Position toView just above screen
CGRect fromViewInitialFrame = [transitionContext initialFrameForViewController:fromVC];
CGRect toViewInitialFrame = toView.frame;
toViewInitialFrame.origin.y -= CGRectGetHeight(toViewInitialFrame);
toViewInitialFrame.origin.x = CGRectGetWidth(fromViewInitialFrame) * 0.5 - CGRectGetWidth(toViewInitialFrame) * 0.5;
toView.frame = toViewInitialFrame;
[containerView addSubview:toView];
// Prevent rotation and adjust bounce
UIDynamicItemBehavior *bodyBehavior = [[UIDynamicItemBehavior alloc]initWithItems:@[toView]];
bodyBehavior.elasticity = 0.7;
bodyBehavior.allowsRotation = NO;
// Add gravity at exaggerated magnitude so animation doesn't seem slow
UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc]initWithItems:@[toView]];
gravityBehavior.magnitude = 10.0f;
// Set collision bounds to include off-screen view and have collision floor in center
// where our final view should come to rest
UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc]initWithItems:@[toView]];
UIEdgeInsets insets = UIEdgeInsetsMake(CGRectGetMinY(toViewInitialFrame), 0.0, CGRectGetHeight(fromViewInitialFrame) * 0.5 - CGRectGetHeight(toViewInitialFrame) * 0.5, 0.0);
[collisionBehavior setTranslatesReferenceBoundsIntoBoundaryWithInsets:insets];
self.collisionBehavior = collisionBehavior;
// Keep track of finish time in case we need to end the animator befor the animator pauses
self.finishTime = duration + self.animator.elapsedTime;
// Closure that is called after every "tick" of the animator
// Check if we exceed duration
__weak ObjcDropOutAnimator *weakSelf = self;
self.action = ^{
__strong ObjcDropOutAnimator *strongSelf = weakSelf;
if (strongSelf)
{
if (strongSelf.animator.elapsedTime >= strongSelf.finishTime)
{
strongSelf.elapsedTimeExceededDuration = YES;
[strongSelf.animator removeBehavior:strongSelf];
}
}
};
// `DropOutAnimator` is a composit behavior, so add child behaviors to self
[self addChildBehavior:collisionBehavior];
[self addChildBehavior:bodyBehavior];
[self addChildBehavior:gravityBehavior];
// Add self to dynamic animator
[self.animator addBehavior:self];
}
// Dismissing Animation
else
{
// Allow rotation and have a elastic item
UIDynamicItemBehavior *bodyBehavior = [[UIDynamicItemBehavior alloc] initWithItems:@[fromView]];
bodyBehavior.elasticity = 0.8;
bodyBehavior.angularResistance = 5.0;
bodyBehavior.allowsRotation = YES;
// Create gravity with exaggerated magnitude
UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc] initWithItems:@[fromView]];
gravityBehavior.magnitude = 10.0f;
// Collision boundary is set to have a floor just below the bottom of the screen
UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc] initWithItems:@[fromView]];
UIEdgeInsets insets = UIEdgeInsetsMake(0, -1000, -225, -1000);
[collisionBehavior setTranslatesReferenceBoundsIntoBoundaryWithInsets:insets];
self.collisionBehavior = collisionBehavior;
// Attachment behavior so view will have effect of hanging from a rope
UIOffset offset = UIOffsetMake(70, -(CGRectGetHeight(fromView.bounds) / 2.0));
CGPoint anchorPoint = CGPointMake(CGRectGetMaxX(fromView.bounds) - 40,
CGRectGetMinY(fromView.bounds));
anchorPoint = [containerView convertPoint:anchorPoint fromView:fromView];
UIAttachmentBehavior *attachBehavior = [[UIAttachmentBehavior alloc] initWithItem:fromView offsetFromCenter:offset attachedToAnchor:anchorPoint];
attachBehavior.frequency = 3.0;
attachBehavior.damping = 0.3;
attachBehavior.length = 40;
self.attachBehavior = attachBehavior;
// `DropOutAnimator` is a composit behavior, so add child behaviors to self
[self addChildBehavior:collisionBehavior];
[self addChildBehavior:bodyBehavior];
[self addChildBehavior:gravityBehavior];
[self addChildBehavior:attachBehavior];
// Add self to dynamic animator
[self.animator addBehavior:self];
// Animation has two parts part one is hanging from rope.
// Part two is bouncying off-screen
// Divide duration in two
self.finishTime = (2./3.) * duration + [self.animator elapsedTime];
// After every "tick" of animator check if past time limit
__weak ObjcDropOutAnimator *weakSelf = self;
self.action = ^{
__strong ObjcDropOutAnimator *strongSelf = weakSelf;
if (strongSelf)
{
if ([strongSelf.animator elapsedTime] >= strongSelf.finishTime)
{
strongSelf.elapsedTimeExceededDuration = YES;
[strongSelf.animator removeBehavior:strongSelf];
}
}
};
}
}
- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
return self.duration;
}
- (void)dynamicAnimatorDidPause:(UIDynamicAnimator *)animator
{
// Animator has reached stasis
if (self.isAppearing)
{
// Check if we are out of time
if (self.elapsedTimeExceededDuration)
{
// Move to final positions
UIView *toView = [self.transitionContext viewControllerForKey:UITransitionContextToViewControllerKey].view;
UIView *containerView = [self.transitionContext containerView];
toView.center = containerView.center;
self.elapsedTimeExceededDuration = NO;
}
// Clean up and call completion
[self.transitionContext completeTransition:![self.transitionContext transitionWasCancelled]];
for (UIDynamicBehavior *behavior in self.childBehaviors)
{
[self removeChildBehavior:behavior];
}
[animator removeAllBehaviors];
self.transitionContext = nil;
}
// Dismissing
else
{
if (self.attachBehavior)
{
// If we have an attachment, we are at the end of part one and start part two.
[self removeChildBehavior:self.attachBehavior];
self.attachBehavior = nil;
[animator addBehavior:self];
NSTimeInterval duration = [self transitionDuration:self.transitionContext];
self.finishTime = 1./3. * duration + [animator elapsedTime];
}
else
{
// Clean up and call completion
UIView *fromView = [self.transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey].view;
UIView *toView = [self.transitionContext viewControllerForKey:UITransitionContextToViewControllerKey].view;
[fromView removeFromSuperview];
toView.userInteractionEnabled = YES;
[self.transitionContext completeTransition:![self.transitionContext transitionWasCancelled]];
for (UIDynamicBehavior *behavior in self.childBehaviors)
{
[self removeChildBehavior:behavior];
}
[animator removeAllBehaviors];
self.transitionContext = nil;
}
}
}
作为复合行为，DropOutAnimator 可以结合许多不同的行为来执行其呈现和消除动画。DropOutAnimator 还演示了如何使用行为的 action 块来检查其项目的位置以及可用于移除在屏幕外移动或截断尚未达到停滞状态的动画的技术所用的时间。
有关更多信息，请参阅 2013 WWDC 会议“使用 UIKit Dynamics 的高级技术” 以及 SOLPresentingFun